Gaseous electric discharge lamp device



Dec. 2l, H. KREFFT GASEOUS ELECTRIC DISCHARGE LAMP DEVICE Filed Aug. 5, 1955 mmh/l we f INVENTOR Q/WVVVLOJVWL BYW Patented Dec. 21, 1937 PATENT OFFICE GASEOUS ELECTRIC DISCHARGE LAMP DEVICE Hermann YKreift, Berlin-Friedrichshagen, Germany, assignor to General Electric Company, a corporation of New York ,Application August 5,

1935, serial No. 34,811

-In Germany August 10, 1934 v5 Claims.

The present invention relates to gaseous electric discharge lamp devices generally.

I have frequently observed that the part of the current-inlead which projects outward from the lamp vessel, is strongly oxidized by the ambient atmosphere and that the oxide layer which forms thereon gradually creeps forward into the hermetic, fused joint between the respective current inleads and the vessel, which loosens said joint and causes gas leaks. This is apt to occur particularly when the current inleads consist of an Y u are at elevated temperatures of several hundred degrees Celsius during operation of the lamp, as is the case, for example, with electric illuminating tubes having a high pressure discharge, such as a high pressure mercury vapor arc discharge, or with electric illuminating tubes which contain the vaporsof metals diiicult to vaporize, such as sodium.

The object of the present invention is to provide means whereby gas leaks caused by oxidation of the external part of thercurrent leads of a gaseous electric discharge device are avoided.` Still further objects and advantages attaching to the device and to its use and operation will be appar ent to those skilled in the art from the following particular description.

Gas leaks at the fuse-in points of the current inleads are effectively avoided when, in accordance with the invention, that part of each current inlead which projects outward from the discharge vessel is enclosed in a hermetically sealed attached vessel which is fused bluntly onto the end part of the discharge vessel and which is evacuated or filled with an inert gas, which attached vessel has one or more outwardly projecting cury rent connection contacts which are connected with the enclosed current inlead or inleads. With such a construction, those parts of the current inlead wires which project directly from the discharge vessel,and which are strongly heated during tube operation are protected from the oxidizing ambient atmosphere by the attached sealed vessel. Oxidation of the electrical contact or contacts on the attached vessel is not apt to occur to a harmful extent since said contacts, being comparatively remote from the discharge vessel are not heated to an extremely elevated temperature during the operation of the device and because these contacts can easily be made of metals or metal alloys which are more resistant to oxidation than the tungsten inleads, for instance chromium, nickel or brass. The relatively large dimensioning of the contacts and the relatively long distance between these and the fuse-in points of the current inleads practically excludes the forward growth of any oxide layer which may form thereon, toward the fuse-in points of the current inlead wires. In the drawing accompanying and forming part of this specification three embodiments of the invention are shown, in which Fig. 1 is a front, partly sectional, view of one end of a gaseous electric discharge lamp embodying the invention,

Fig. 2 is a similar View of another embodiment of the invention, and

Fig. 3 is a similar view of still another embodiment o'f the invention.

Like numbers denote like parts in all the figures.

Referring to Fig. l of the drawing the lamp Vessel I, which is hermetically sealed and is filled with desired gases, vapors or a gas-vapor mixture, has at the end thereof a neck piece 2 which is fused to the iiared edge 3 of a stem 4. Said stem 4 has a nipple 5 which projects outward and into which the current inlead and support-wire 6 of an electrode 1, directly heated by the discharge, is fused' gas tight. Said electrode 'I consists of a wound strip .of metal gauze, such as tungsten gauze, which is impregnated with an electron emitting material, such as barium oxide. Onto the neck part 2 agtubular glass member 8 is bluntly fused, which member 8 concentrically surrounds the nipple 5 and the outer part 9 of the current inlead wire 6 which projects from the nipple. Into the outer rim of the member 8, the ring I of a metallic sealing cap II is fused gas tight, which ring I0 is sharpened in wedge shape. On this cap II, an outwardly projecting threaded bolt I2 is attached, which together with a nut I3 forms a terminal contact for fastening a current conductor. A screw I4 is affixed to the inner wall of the cap II, which screw serves to fasten a spring I which is connected with the thickened end I6 of the current inlead wire part 9. The connection between the cap II and the current inlead wire part 9 is thus made flexible. The attached vessel iinally also has an evacuating tube which, afterthe attached vessel is evacuated and in a given case is filled with inert gas, such as argon, is sealed off from the evacuating system.

The embodiment of the invention shown in Fig. 2 is similar in all respects to that shown in Fig. 1 except that in this embodiment a flexible transition part I8 is provided between the cap II and the outwardly projecting threaded bolt I2 so that the threaded bolt I2 is somewhat movable in re- 1 tight.

spring I 5 of the embodiment shown in Fig. 1 is not necessary and the outer part 9 of the current inlead 4wire 6, as shown, can be lead directly through the threaded bolt l2 and can be weide thereto at the outer end 2.0 thereof.

In the embodiment shown in Fig. 3 the flared stem 3, 4 ,is provided with a pinch 2| into which two current inleads 6 and 6' are fused vacuum Said leads 6 and 6' support an indirectly heated electrode consisting of a heating wire helix 22, such as a tungsten filament, wrapped around a rod 23 of electron emitting material, such as a compacted, sintered rod comprising barium oxide. The sealing cap I I, by means of a ring I0 which is sharpened wedge shaped, is again fused gas tight onto the attached member 8 which is fused to the neck part 2 of the illuminating tube vessel I the joint therebetween being a hermetic one. The outwardly projecting bolt I2 is set into the cap II by means of an electrically insulating sleeve 24. At the inner part of the threaded bolt I2 a screw 25 is aiixed for fastening a. spring 26 which establishes connection between the one -outer current inlead wire part 9 and the connection contact consisting of the screw I2 and the nut I3. At the side of the cap II a second contact is provided which also consists of a projecting threaded bolt 21 and a nut 28. By means of a screw 29 and a spring 30 this second Contact 21 and-28 is connected with the second outer current inlead wire part 9. With this current inlead, as with the construction forms according to Figs. 1 and 2, the attached vessel is also provided with an evacuating tube I'I and is either evacuated or lled with an inert gas.

It will be understood that the other end of a complete lamp device made in accordance with the present invention has the same structurel asV the end of the-lamp shown in the dierent figures of the drawing, when desired, and that numerous changes in the form and details of the device can be made by those skilled in the art without departing from the spirit and'scope of the invention.

What I claim as newand desire to secure by Letters Patent of the United States, is:-

1. A base for a gaseous electric discharge lamp device, said lamp device comprising a container having a stem protruding therefrom and a current lead of easily oxidizable material sealed into said stem and projecting therefrom, said base being a hollow, hermetically-sealed vessel fused to said lamp container and enclosing said stem and the part of said lead projecting outwardly therefrom, said base having an electrical contact mounted thereon at the'end thereof remote from aioaosr said lamp container, the outwardly projecting part of said current lead in said base being attached to said contact, a portion of the structure' comprising said lead and said base being flexible.

2. A base for a gaseous electric discharge lamp device, said lamp device comprising a container having a stem protruding therefrom and a current lead of easily oxidizable material sealed into said stem and projecting therefrom, said base being a hollow, hermetically sealed vessel fused to said lamp container and enclosing said stem and the part of said lead projecting outwardly therefrom, said base having .an electrical contact mounted thereon at the end thereof remote from said lamp container, the outwardly projecting part of said current lead in said base being attached to said contact, a portionv of said base between said lead and the part of said base fused to said lamp container being flexible.

3. A base for a gaseous electric discharge lamp device, said lamp device comprising a container having a stem protruding therefrom and a current lead of easily oxidizable material sealed into said stem and projecting therefrom, said base being a hollow, hermetically sealedl vessel fused to said lamp container and enclosing said stem and the part of said lead projecting outwardly therefrom, said base having an electrical contact mounted thereon at the end'thereof remote from said lamp container,y the .outwardly projecting part of said current lead in said base being attached to said contact.

4. A base for a gaseous electric discharge lamp device, said lamp device comprising a container' having a stem protrudingl therefrom and a current lead of easily oxidizable material sealed into said stem and projecting therefrom, said base being a hollow, hermetically sealed vessel fused to said lamp container and enclosing said stem and the part of said lead projecting outwardly therefrom, said base having an electrical contact mounted thereon at the end thereof remote from said`lamp container, the outwardly projecting part of said current lead in said base being exible and being attached to said contact.

5. A base for a gaseous electric discharge lamp device, said lamp device comprising a 4container having a stem protruding therefrom and a current lead of easily oxidizable material sealed into said stem and projecting therefrom, said base being a hollow, evacuated,l hermetically sealed vessel fused to said lamp container and enclosing said stem and the part of said lead projecting outwardly therefrom, said base having an electrical contact mounted thereon at the end thereof remote from said lamp container, the outwardly projecting part of the current lead of said lamp in said base being attached to said contact.

HERMANN KREFF'I. 

